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   Table of Contents      
ORIGINAL ARTICLE
Year : 1997  |  Volume : 45  |  Issue : 4  |  Page : 211-214

Evaluation of the role of syringing prior to cataract surgery


Schell Eye Hospital, Christian Medical College, Vellore, India

Correspondence Address:
R Thomas
Schell Eye Hospital, Christian Medical College, Vellore
India
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Source of Support: None, Conflict of Interest: None


PMID: 9567015

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  Abstract 

Patients for cataract surgery in India routinely undergo preoperative syringing to rule out chronic dacryocystitis. We determined the sensitivity and specificity of the clinical test of regurgitation on pressure over the lacrimal sac (ROPLAS) as a screening test for chronic dacryocystitis and compared it to syringing. 621 consecutive outpatients who needed syringing for various reasons (including 318 who had routine syringing prior to cataract surgery) were examined in a masked manner for regurgitation on pressure over the lacrimal sac. They then underwent syringing by a trained (masked) observer. The sensitivity and specificity of ROPLAS were 93.2% and 99.3%, respectively. Using a 6.6% prevalence of chronic dacryocystitis (the prevalence in our cataract population), the negative predictive value of the test was 99.5%. In the presence of regurgitation of pressure over the sac, the high specificity of ROPLAS confirms chronic dacryocystitis. In view of the opportunity costs, when ROPLAS is negative, preoperative syringing in cataract is perhaps unnecessary, unless the findings are equivocal or the index of suspicion for chronic dacryocystitis is very high.

Keywords: Syringing, chronic dacryocystitis, cataract


How to cite this article:
Thomas R, Thomas S, Braganza A, Muliyil J. Evaluation of the role of syringing prior to cataract surgery. Indian J Ophthalmol 1997;45:211-4

How to cite this URL:
Thomas R, Thomas S, Braganza A, Muliyil J. Evaluation of the role of syringing prior to cataract surgery. Indian J Ophthalmol [serial online] 1997 [cited 2020 Aug 13];45:211-4. Available from: http://www.ijo.in/text.asp?1997/45/4/211/14999



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PPV IS POSITIVE PREDICTIVE VALUE NPV IS NEGATIVE PREDICTIVE VALUE

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PPV IS POSITIVE PREDICTIVE VALUE NPV IS NEGATIVE PREDICTIVE VALUE

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NLD IS NASOLACRIMAL DUCT

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NLD IS NASOLACRIMAL DUCT

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India has a large cataract blind population as well as a steadily increasing backlog of cases. Each year, 1.6 to 1.9 million cataract operations are performed throughout the country,[1] many in "camps" or rural peripheral centers. In most centers, preoperative syringing of the nasolacrimal system is routinely performed prior to cataract surgery; the aim is to exclude chronic dacryocystitis, a major risk factor for postoperative endophthalmitis.

Syringing is usually performed by a trained nurse or ophthalmic assistant and is invasive; a small percentage of syringings will be equivocal and require repetition or confirmation of findings by the ophthalmologist. We determined the sensitivity and specificity of the clinical test of regurgitation on pressure over the lacrimal sac (ROPLAS) as a screening examination for chronic dacryocystitis and compared it to syringing.


  Materials and Methods Top


621 consecutive outpatients who required syringing for various reasons such as epiphora, corneal ulcers or routine cataracts were included in the study.

These patients were initially examined by their ophthalmologist in the outpatient department. A history of complaints related to lacrimal system was obtained from each patient. In addition to the usual clinical examination, the following maneuvers were performed.


  Regurgitation on pressure over the lacrimal sac Top


The anterior lacrimal crest was identified by tracing the inferior orbital margin medially and superiorly. The index finger was then directed behind the crest and used to apply pressure on the sac area in an upward and medial direction so as to express the contents of the lacrimal sac into the conjunctiva. Any reflux of fluid or purulent material from the puncta was noted. The remainder of the ophthalmic examination was completed and after one hour the patient was sent for syringing.


  Syringing Top


Syringing was performed in a masked manner by a trained nurse. The patient was placed in a supine position and a topical anesthetic (4% lignocaine) placed in the eye. The lower punctum was dilated (if necessary) with a punctum dilator; a blunt lacrimal cannula connected to a 5cc syringe (containing normal saline) was inserted into the inferior canaliculus. A soft stop indicated canalicular obstruction. A hard stop indicated that the canaliculus was patent. The canaliculus was then irrigated (regardless of the type of stop) and any reflux of fluid or discharge from the upper or the lower canaliculus was noted. The patient was asked whether the fluid had reached the pharynx. If syringing could not be performed through the inferior canaliculus, the superior canaliculus was utilized. These findings were noted and communicated to the study coordinator. A suspected partial block was confirmed by "pressure" syringing: syringing done while the opposite canaliculus was occluded with a punctum dilator. Inferences were made as shown in [Table - 1].

The results were analyzed using a 2 x 2 table dividing the patients into syringing "free" (including partially free) or "blocked"; and regurgitation on pressure present or absent. Each eye was considered separately and syringing was considered the gold standard. However, the prevalence data is quoted for the patient and not for the eye. The sensitivity, specificity, as well as positive and negative predictive values were calculated from 2 x 2 tables as shown in [Table - 2].


  Results Top


Of 621 patients 279 were males and 342 females. 135 patients had complaints pertaining to the lacrimal system. The analysis of all the study patients is shown in [Table - 3]. The sensitivity of the clinical test ROPLAS was 93.2%, and the specificity 99.3%. The overall prevalence of chronic dacryocystitis amongst the patients was 18.4%. Using this prevalence, the positive predictive value of ROPLAS was 93.89%, and the negative predictive value 99.2%

For the entire group, patients with and without complaints of epiphora were analyzed separately. For patients with complaints the sensitivity and specificity of ROPLAS were 94.7% and 99.4%, respectively [Table - 4]. For those without complaints, the sensitivity and specificity were 89.5% and 99.3%, respectively [Table - 5].

The 318 cataract patients undergoing routine syringing were assessed separately [Table - 6]. ROPLAS had a sensitivity of 88.9% and specificity of 99.0%. The prevalence of chronic dacryocystitis in this cataract population was 6.6% Using this value for prevalence, the negative predictive value of ROPLAS was 99.5%. For the subset of cataract patients without complaints the sensitivity was 85%; specificity and negative predictive value was the same as that of the total cataract population (99.0% and 99.5%, respectively; [Table - 7]. In the subgroup of cataract patients with complaints (n=14), all the patients with blocked ducts on syringing were detected on ROPLAS (sensitivity 100%); all with patent ducts were so identified (100%).

For the entire group, the sensitivity, specificity, positive predictive value, and negative predictive value of complaints of epiphora alone in comparison to syringing was 70.3%, 83.4%, 30.7%, and 96.4%, respectively.


  Discussion Top


India's cataract blind population necessitates a large number of cataract operations. In order to identify those with chronic dacryocystitis (and therefore at risk for postoperative endophthalmitis), syringing prior to cataract surgery has been the routine in most centers in our country. In the West, routine pre-cataract evaluation does not include irrigation of the lacrimal drainage system unless specific complaints are present.

Syringing is a simple confirmatory test for documenting chronic dacryocystitis, the extent (partial or complete) of obstruction and its location (canalicular, nasolacrimal duct). However, syringing the lacrimal passages does have potential complications such as pain, discomfort, ecchymosis, lid edema, and creation of a false passage.

There is also the time commitment to consider. If we take approximately 3 minutes to syringe one patient, 2 million cataracts (the approximate number of cataract operations performed annually) would require 6 million minutes (100,000 man hours; 4,167 man days) or 11.42 person years annually. Even if only 5% of the patients undergoing syringing need to be rechecked by the ophthalmologist, this entails 208 (ophthalmologist) days. Assuming an 8 hour working day, this involves 624 (ophthalmologist) working days every year. If an ophthalmologist can perform two cataract operations every hour, the opportunity cost of syringing is approximately 10,000 cataracts each year. Clearly, there is a need for a simple, reliable test to rule out chronic dacryocystitis.

ROPLAS is a clinical test to determine the reflux of fluid through the puncta, indicating a block in the nasolacrimal duct and dacryocystitis. This is a rapid, non invasive clinical test easily performed by the ophthalmologist during the course of the ophthalmic examination. We found that this test had a specificity of 99.0%. The high specificity indicates that if ROPLAS is positive, chronic dacryocystitis is almost certainly present. A high specificity rules in the disease.[2]

While the sensitivity of the test per se is not good enough to rule out chronic dacryocystitis (if test is negative), the negative predictive value in routine cataract patients was 99.5%. If we screen 200 cataract patients using ROPLAS, we would miss only one chronic dacryocystitis. Chronic dacryocystitis is certainly a major risk factor for postoperative endophthalmitis, a devastating complication; it could be argued that the time spent in the detection of this risk factor is therefore worthwhile. However, the actual risk of postoperative endophthalmitis in chronic dacryocystitis (especially in cases mild enough to be missed on pressure over the sac) is unknown. Endophthalmitis is not an inevitable outcome if cataract surgery is inadvertently performed in the presence of chronic dacryocystitis. Ancedotally, we have two cases where chronic dacryocystitis missed on syringing was detected by ROPLAS 6 days and 2 weeks after cataract surgery. Neither of the patients developed endophthalmitis in that period; both underwent emergency dacryocystorhinostomy according to recommended practice. Also, in this study, four cases of atonic sac considered free on syringing were detected by pressure over the sac.

The prevalence of chronic dacryocystitis in our cataract population (6.6%) seems fairly high and is probably related to the socioeconomic status of our population. If the prevalence is lower, the negative predictive value would be higher. For example, if the prevalence was only 1%, the negative predictive value would be 99.9%. In this situation only one chronic dacryocystitis would be missed in 909 cases. The negative predictive value would decrease with a higher prevalence.

Our study indicates that routine preoperative syringing of cataract patients is probably unnecessary. In this setting a positive ROPLAS (with a specificity of over 99%) confirms chronic dacryocystitis rendering syringing superfluous for its detection. Also the negative predictive value of a negative ROPLAS almost excludes chronic dacryocystitis.

The study results would not be applicable if ROPLAS is not performed as described. If confirmatory repetition of ROPLAS by another observer (or indeed syringing) is deemed necessary, enough time should be given for the discharge to reaccumulate. Also, in the unlikely event that the prevalence of chronic dacryocystitis is higher than in our study, the ophthalmologist should calculate the negative predictive value for his own population before making a decision about the role of syringing; we have provided the basis for such calculations and decisions. However, for routine cataract surgery it would seem that preoperative syringing can be restricted to cases with a high index of suspicion for chronic dacryocystitis, patients with equivocal ROPLAS, and perhaps one eyed patients.

 
  References Top

1.
Jose R, Bachani D. World Bank assisted cataract blindness control project. Indian J Ophthalmol 1995;43:35-43.  Back to cited text no. 1
[PUBMED]    
2.
Sackett DL, Haynes RB, Guyatt GH, Tugwell P. Clinical Epidemiology: A Basic Science for Clinical Medicine. 2nd ed. Boston: Little, Brown and Company; 1991. p 69-152.  Back to cited text no. 2
    



 
 
    Tables

  [Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7]



 

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